How Was This So Valuable?

I still don't understand how these swords were worth this much. I love just mining things and making tons and tons of money so naturally this game was so fun to play. Hopefully next time I can find even rarer ores so I make more and more valuable swords. Game: Forge Ahead- https://play.google.com/store/apps/de... Music provided by: (Epidemic Sound) http://www.epidemicsound.com/ (Vexento)    / @vexento